adding negative binary base conversion algorithms

conversions/int_to_negative_binary_base.py

@@ -0,0 +1,30 @@
+def decimal_to_negative_binary(number: int) -> int:
+    """
+    a conversion algorithm from decimal
+    to negative binary base
+
+    https://en.wikipedia.org/wiki/Negative_base#:~:text=Binary-,Negabinary,-Ternary
+
+    >>> decimal_to_negative_binary(10)
+    11110
+    >>> decimal_to_negative_binary(-10)
+    1010
+    >>> decimal_to_negative_binary(-30)
+    100110
+    >>> decimal_to_negative_binary(30)
+    1100010
+    """
+
+    if number == 0:
+        return 0
+    result_str = ""
+    while number != 0:
+        number, remainder = divmod(number, -2)
+        if remainder < 0:
+            number, remainder = number + 1, remainder + 2
+        result_str = str(remainder) + result_str
+    return int(result_str)
+
+
+if __name__ == "__main__":
+    __import__("doctest").testmod()

conversions/negative_binary_base_to_int.py

@@ -0,0 +1,24 @@
+def negative_binary_to_int(negative_binary: int) -> int:
+    """
+    a conversion algorithm from negative binary
+    base to decimal
+
+    https://en.wikipedia.org/wiki/Negative_base#:~:text=Binary-,Negabinary,-Ternary
+
+    >>> negative_binary_to_int(101110)
+    -38
+    >>> negative_binary_to_int(10111110)
+    -150
+    >>> negative_binary_to_int(100)
+    4
+    >>> negative_binary_to_int(110)
+    2
+    """
+    negative_binary_str = str(negative_binary)
+    r = negative_binary_str[::-1]
+    res = [int(r[c]) * (-2) ** c for c in range(len(r))]
+    return sum(res)
+
+
+if __name__ == "__main__":
+    __import__("doctest").testmod()